Early warning system for algae

Wood researchers foresee infestations on house facades

Macroscopic image of a plaster with algae infestation WKI
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Green is the color of hope. On the other hand, she does not like to see house facades. Especially there, however, the green is spreading more and more in the form of algae growth. Fraunhofer researchers can now predict if and when a homeowner will have to reckon with these microorganisms. This will enable consumers to reliably assess the quality of house cleaning in terms of their algae resistance in the future.

One reason for the strong algae growth is the increased use of diesel vehicles. The emitted nitrogen oxides deposit on facades and serve the unwanted roommates as a source of food. Another reason is the better insulation of many buildings. It leads to colder wall surfaces on which water condenses. This moisture provides an ideal habitat for algae.

How algae-resistant is the house facade?

Of course, builders would like to know how likely and within what time frame algae are to be expected on their plaster in order to switch to an alternative product if necessary. The scientists at the Fraunhofer Institute for Wood Research, Wilhelm-Klauditz-Institut (WKI), are currently developing a procedure for such prognoses. It qualifies plasters quickly and reliably.

Irregular algae infestation on a plaster facade with thermal insulation system © WKI

The Braunschweig researchers are planning to introduce a classification scheme similar to the classification of refrigerators into energy efficiency classes. Builders at a glance have a reliable basis for deciding on the algae resistance of their house facade.

A plaster is evaluated in two steps. First, it is examined whether and if so in what quantity and for what period of time the plaster forms moisture on its surface. A second examination step allows conclusions as to whether the plaster may contain substances that prevent algae growth. display

First test successful

First series of tests already provide convincing results and allow a speedy market maturity of this process. Thus, the plaster industry would be available in a reliable quality criterion. It could be offensively marketed and kept the competition of low-cost suppliers at a distance.

In an additional step, the question can then be answered as to whether the immediate surroundings of a building object can be expected to cause algae growth. However, this complex procedure must take into account many complex constraints, so that it is likely to be larger in the first instance and reserved for commercial construction projects.

(idw - Fraunhofer-Gesellschaft, 29.10.2007 - DLO)